We present the case of a 57-year-old woman with severe aortic regurgitation and ventricular dysfunction (ejection fraction 34%) requiring surgical intervention. In pre-operative period, no left ventricular (LV) asynchrony was detected by QRS duration and current echocardiographic techniques, including tissue Doppler imaging. A new echocardiographic technology, the timing of regional volumetric changes by three-dimensional echocardiography (3DEcho), demonstrated an intraventricular mechanical asynchrony. Indeed, during surgery, epicardial leads were attached to the right atrium and the right ventricle as part of the standard management. Two additional epicardial leads were attached to the left ventricle on the most delayed wall localized precisely by 3DEcho on the inferolateral wall. In post-operative period, biventricular (BiV) pacing showed improvement in the LV mechanical synchronization, resulting in improvement in the LV systolic function compared with right ventricular pacing or no pacing. This case shows the potential utility of 3DEcho in prediction of favourable response of the BiV pacing in patients with depressed LV systolic function ongoing cardiac surgery.